Methods and apparatus for delivering staples to a target tissue

ABSTRACT

A device for attaching a sheet-like implant to a target tissue includes a pilot member and a staple push rod. In some embodiments, the pilot member has a distal end and at least a pair of prongs extending from the distal end. The prongs are configured to form pilot holes when the distal end of the pilot member is pressed against the target tissue. The staple push rod is disposed within at least a portion of the pilot member and slidable relative thereto. The staple push rod includes at least a pair of stakes. Each stake is dimensioned to engage a surface of a staple to apply pushing forces thereto. Each stake is positioned relative to a prong along an inner surface of the pilot member so that the stakes advance into the pilot holes when the stakes are moved in a distal direction. Methods for attaching a sheet-like implant to a target tissue are also disclosed

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. Ser. No. 12/794,551filed on Jun. 4, 2010, which claims the benefit of: U.S. ProvisionalPatent Application Ser. No. 61/184,198 filed on Jun. 4, 2009; U.S.Provisional Patent Application Ser. No. 61/253,800 filed on Oct. 21,2009; and U.S. Provisional Patent Application No. 61/313,051 file onMar. 11, 2010, the disclosures of each are incorporated herein byreference in their entirety.

INCORPORATION BY REFERENCE

The present application is related to U.S. patent application Ser. No.12/794,540, (Attorney Docket No. 10322-705.200), entitled Methods andApparatus for Fixing Sheet-like Materials to a Target Tissue, filed onJun. 4, 2010; U.S. patent application Ser. No. 12/794,673, (AttorneyDocket No. 10322-705.202), entitled Methods and Apparatus for DeployingSheet-like Materials, filed on Jun. 4, 2010; and, U.S. patentapplication Ser. No. 12/794,677, (Attorney Docket No. 10322-705.203),entitled Methods and Apparatus Having a Bowstring-like Staple Deliveryto a Target Tissue, filed on Jun. 4, 2010, the disclosures of eachincorporated herein by reference.

All publications and patent applications mentioned in this specificationare herein incorporated by reference to the same extent as if eachindividual publication or patent application was specifically andindividually indicated to be incorporated by reference.

FIELD OF THE INVENTION

The present invention relates generally to orthopedic medicine andsurgery. More particularly, the present invention relates to methods andapparatus for delivery and fixation of sheet-like materials, such as fortreating articulating joints.

BACKGROUND OF THE INVENTION

The glenohumeral joint of the shoulder is found where the head of thehumerus mates with a shallow depression in the scapula. This shallowdepression is known as the glenoid fossa. Six muscles extend between thehumerus and scapula and actuate the glenohumeral joint. These sixmuscles include the deltoid, the teres major, and the four rotator cuffmuscles. As disclosed by Ball et al. in U.S. Patent Publication No. US2008/0188936 A1 and as illustrated in FIG. 1 the rotator cuff musclesare a complex of four muscles. These four muscles are the supraspinatus,the infraspinatus, the subscapularis, and the teres minor. The centeringand stabilizing roles played by the rotator cuff muscles are critical tothe proper function of the shoulder. The rotator cuff muscles provide awide variety of moments to rotate the humerus and to oppose unwantedcomponents of the deltoid and pectoralis muscle forces.

The four muscles of the rotator cuff arise from the scapula 12. Thedistal tendons of the rotator cuff muscles splay out and interdigitateto form a common continuous insertion on the humerus 14. Thesubscapularis 16 arises from the anterior aspect of the scapula 12 andattaches over much of the lesser tuberosity of the humerous. Thesupraspinatus muscle 18 arises from the supraspinatus fossa of theposterior scapula, passes beneath the acromion and the acromioclavicularjoint, and attaches to the superior aspect of the greater tuberosity 11.The infraspinatus muscle 13 arises from the infraspinous fossa of theposterior scapula and attaches to the posterolateral aspect of thegreater tuberosity 11. The teres minor 15 arises from the lower lateralaspect of the scapula 12 and attaches to the lower aspect of the greatertuberosity 11.

The mechanics of the rotator cuff muscles 10 are complex. The rotatorcuff muscles 10 rotate the humerus 14 with respect to the scapula 12,compress the humeral head 17 into the glenoid fossa providing a criticalstabilizing mechanism to the shoulder (known as concavity compression),and provide muscular balance. The supraspinatus and infraspinatusprovide 45 percent of abduction and 90 percent of external rotationstrength. The supraspinatus and deltoid muscles are equally responsiblefor producing torque about the shoulder joint in the functional planesof motion.

The rotator cuff muscles 10 are critical elements of this shouldermuscle balance equation. The human shoulder has no fixed axis. In aspecified position, activation of a muscle creates a unique set ofrotational moments. For example, the anterior deltoid can exert momentsin forward elevation, internal rotation, and cross-body movement. Ifforward elevation is to occur without rotation, the cross-body andinternal rotation moments of this muscle must be neutralized by othermuscles, such as the posterior deltoid and infraspinatus. The timing andmagnitude of these balancing muscle effects must be preciselycoordinated to avoid unwanted directions of humeral motion. Thus thesimplified view of muscles as isolated motors, or as members of forcecouples must give way to an understanding that all shoulder musclesfunction together in a precisely coordinated way—opposing musclescanceling out undesired elements leaving only the net torque necessaryto produce the desired action. Injury to any of these soft tissues cangreatly inhibit ranges and types of motion of the arm.

With its complexity, range of motion and extensive use, a fairly commonsoft tissue injury is damage to the rotator cuff or rotator cufftendons. Damage to the rotator cuff is a potentially serious medicalcondition that may occur during hyperextension, from an acute traumatictear or from overuse of the joint. With its critical role in abduction,rotational strength and torque production, the most common injuryassociated with the rotator cuff region is a strain or tear involvingthe supraspinatus tendon. A tear in the supraspinitus tendon 19 isschematically depicted in FIG. 2. A tear at the insertion site of thetendon with the humerus, may result in the detachment of the tendon fromthe bone. This detachment may be partial or full, depending upon theseverity of the injury. Additionally, the strain or tear can occurwithin the tendon itself. Injuries to the supraspinatus tendon 19 andrecognized modalities for treatment are defined by the type and degreeof tear. The first type of tear is a full thickness tear as alsodepicted in FIG. 2, which as the term indicates is a tear that extendsthrough the thickness of the supraspinatus tendon regardless of whetherit is completely torn laterally. The second type of tear is a partialthickness tear which is further classified based on how much of thethickness is torn, whether it is greater or less than 50% of thethickness.

The accepted treatment for a full thickness tear or a partial thicknesstear greater than 50% includes reconnecting the torn tendon via sutures.For the partial thickness tears greater than 50%, the tear is completedto a full thickness tear by cutting the tendon prior to reconnection. Incontrast to the treatment of a full thickness tear or a partialthickness tear of greater than 50%, the treatment for a partialthickness tear less than 50% usually involves physical cessation fromuse of the tendon, i.e., rest. Specific exercises can also be prescribedto strengthen and loosen the shoulder area. In many instances, theshoulder does not heal and the partial thickness tear can be the sourceof chronic pain and stiffness. Further, the pain and stiffness may causerestricted use of the limb which tends to result in further degenerationor atrophy in the shoulder. Surgical intervention may be required for apartial thickness tear of less than 50%, however, current treatmentinterventions do not include repair of the tendon, rather the surgicalprocedure is directed to arthroscopic removal of bone to relieve pointsof impingement or create a larger tunnel between the tendon and bonethat is believed to be causing tendon damage. As part of the treatment,degenerated tendon may also be removed using a debridement procedure inwhich tendon material is ablated. Again, the tendon partial tear is notrepaired. Several authors have reported satisfactory early postoperative results from these procedures, but over time recurrentsymptoms have been noted. In the event of recurrent symptoms, many timesa patient will “live with the pain”. This may result in less use of theaim and shoulder which further causes degeneration of the tendon and maylead to more extensive damage. A tendon repair would then need to bedone in a later procedure if the prescribed treatment for partial tearwas unsuccessful in relieving pain and stiffness or over time the tearpropagated through injury or degeneration to a full thickness tear or apartial thickness tear greater than 50% with attendant pain anddebilitation. A subsequent later procedure would include the moredrastic procedure of completing the tear to full thickness and suturingthe ends of the tendon back together. This procedure requires extensiverehabilitation, has relatively high failure rates and subjects thepatient who first presented and was treated with a partial thicknesstear less than 50% to a second surgical procedure.

As described above, adequate treatments do not currently exist forrepairing a partial thickness tear of less than 50% in the supraspinatustendon. Current procedures attempt to alleviate impingement or make roomfor movement of the tendon to prevent further damage and relievediscomfort but do not repair or strengthen the tendon. Use of the stilldamaged tendon can lead to further damage or injury. Prior damage mayresult in degeneration that requires a second more drastic procedure torepair the tendon. Further, if the prior procedure was only partiallysuccessful in relieving pain and discomfort, a response may be to usethe shoulder less which leads to degeneration and increased likelihoodof further injury along with the need for more drastic surgery. There isa large need for surgical techniques and systems to treat partialthickness tears of less than 50% and prevent future tendon damage bystrengthening or repairing the native tendon having the partialthickness tear.

SUMMARY OF THE INVENTION

According to aspects of the invention, a device for attaching asheet-like implant to a target tissue is disclosed. In some embodiments,the device includes a pilot member and a staple push rod. In theseembodiments, the pilot member has a distal end and at least a pair ofprongs extending from the distal end. The prongs are configured to formpilot holes when the distal end of the pilot member is pressed againstthe target tissue. The staple push rod is disposed within at least aportion of the pilot member and slidable relative thereto. The staplepush rod includes at least a pair of stakes. Each stake is dimensionedto engage a surface of a staple to apply pushing forces thereto. Eachstake is positioned relative to a prong along an inner surface of thepilot member so that the stakes advance into the pilot holes when thestakes are moved in a distal direction.

In some embodiments of the invention, the stakes are biased to expandagainst an inner surface of the pilot member. Each stake has a distalportion and a proximal portion. Each distal portion may be dimensionedto extend into a passage defined by a staple. Each proximal portion mayhave a width larger than a width of each distal portion so that ashoulder of each proximal portion contacts a proximal surface of thestaple to apply pushing forces thereto.

In some embodiments, the device also includes a staple which is carriedby the staple push rod. The staple includes first and second arms, eachhaving proximal and distal ends. A bridge extends from the proximal endof the first aim to the proximal end of the second arm. A first fluke ofthe staple has a proximal end abutting the distal end of the first arm.A second fluke of the staple has a proximal end abutting the distal endof the second arm. In some of these embodiments, each stake of thestaple push rod has a distal portion and a proximal portion. Each distalportion extends into a passage defined by a fluke. Each proximal portionhas a width larger than a width of each distal portion. This allows ashoulder of each proximal portion to contact a distal surface of a fluketo apply pushing forces thereto. The pushing forces place the first arm,the second arm, and the bridge in tension when the flukes are pushedinto the target tissue. Each stake may be configured to bend at alocation slightly distal of the shoulder when each fluke rotates.

In some embodiments, the proximal portion of each stake has a proximalthickness, and the distal portion of each stake has a distal thickness.The distal thickness may be configured to be less than the proximalthickness to facilitate bending of each stake at a location slightlydistal of each shoulder. In some embodiments, each stake bends proximatethe proximal end of a fluke when the flukes rotate. The proximalportions of the stakes may be configured with sufficient length so thatthere is a gap between the staple push rod and the bridge portion ofstaple. This allows the staple to be placed in tension without thebridge portion of the staple contacting the staple push rod.

In some embodiments, each prong of the pilot member has a length that isgreater than a length of each fluke of the staple. The device may beconfigured such that the pushing forces include a first force applied toa proximal surface of the first fluke at a location that is offset fromthe first arm. The proximal portions of the stakes may be biased todiverge from one another so that the pushing force applied to each flukehas a laterally outward component. In some embodiments, a distal-mostportion of each stake extends across a leading edge of each fluke.

According to aspects of the invention, methods for attaching asheet-like implant to target tissue are also disclosed. In someembodiments, the methods include the step of providing a device thatincludes a pilot member. The pilot member has a distal end and at leasta pair of prongs extending from the distal end. The device furtherincludes a staple push rod carrying a staple. The staple comprises firstand second arms each having proximal and distal ends. A bridge extendsfrom the proximal end of the first arm to the proximal end of the secondarm. The staple further comprises a first fluke having a proximal endabutting the distal end of the first arm, and a second fluke having aproximal end abutting the distal end of the second arm. The staple pushrod of the device includes a pair of stakes, each having distal andproximal portions. Each distal portion extends into a passage defined bya fluke. Each proximal portion has a width larger than a width of eachdistal portion so that a shoulder of each proximal portion contacts adistal surface of a fluke.

The above methods further include the step of piercing the target tissuewith the first prong of the pilot member to create a first pilot hole,and piercing the target tissue with the second prong to create a secondpilot hole. The first fluke is positioned near the first pilot hole andthe second fluke is positioned near the second pilot hole. The staplepush rod is advanced in a distal direction so that the stakes applypushing forces to the flukes. This causes the flukes to advance into thepilot holes and causes the first arm, the second arm, and the bridge tobe placed in tension. The first arm provides a first reaction force whenplaced in tension and the second arm provides a second reaction forcewhen placed in tension. The pushing forces and reaction forces cooperateto produce a moment applied to each fluke. The moment applied to eachfluke causes each fluke to rotate so that each fluke assumes a lockedposition. When in the locked position, the longitudinal axis of eachfluke is skewed relative to a longitudinal axis of the pilot member.

In some embodiments, a first moment having a first direction is appliedto the first fluke, and a second moment having a second direction isapplied to the second fluke. In these embodiments, the first directionis different from the second direction. In some embodiments, the firstdirection is generally opposite the second direction. The firstdirection may be a clockwise direction while the second direction is acounter-clockwise direction. In some embodiments, a first pushing forceis applied to the proximal surface of the first fluke at a location thatis offset from the first arm. The first pushing force may be in adirection that is generally parallel to a central axis of the firstpilot hole.

In some embodiments, the flukes are advanced into the pilot holes whilethe prongs are disposed in the pilot holes. The methods may furtherinclude the step of moving the pilot member in a proximal directionrelative to the target tissue until a distal end of the first prong islocated proximal of the first fluke and a distal end of the second prongis located proximally of the second fluke. The step of advancing thestaple push rod in a distal direction may include actuating a mechanismthat produces relative motion between the staple push rod and the pilotmember while applying a distally directed force to the pilot member.

In some of the above embodiments, moving the pilot member in a proximaldirection relative to the target tissue includes producing relativemotion between the staple push rod and the pilot member while applying adistally directed force to the pilot member. The first fluke may assumea first locking position and the second fluke may assume a secondlocking position while a distal end of the first prong is locatedproximal of the first fluke and a distal end of the second prong islocated proximally of the second fluke.

According to aspects of the invention, a device for attaching asheet-like implant to a target tissue is disclosed. In some embodimentsthe device includes a pilot member, a staple push rod slidably disposedwithin at least a portion of the pilot member, and a staple carried bythe push rod. In these embodiments, the pilot member has a distal endand at least a pair of prongs extending from the distal end. The staplecomprises first and second arms, each having proximal and distal ends. Abridge extends from the proximal end of the first aim to the proximalend of the second arm. A first fluke of the staple has a proximal endabutting the distal end of the first arm, and a second fluke of thestaple has a proximal end abutting the distal end of the second arm. Thestaple push rod includes a pair of stakes, each having distal andproximal portions. The distal portion of each stake extends into apassage defined by a fluke. Each proximal portion has a width largerthan a width of each distal portion.

With the above arrangement, a shoulder of each proximal portion contactsa distal surface of a fluke to apply pushing forces thereto. The pushingforces place the first arm, the second arm, and the bridge in tensionwhen the flukes are pushed into the target tissue. The first armprovides a first reaction force when placed in tension, and the secondarm provides a second reaction force when placed in tension. The pushingforces and the reaction forces cooperate to produce a moment applied toeach fluke. The moment applied to each fluke causes each fluke to rotateso that each fluke assumes a locked position. When in the lockedposition, the longitudinal axis of each fluke is skewed relative to anarm of the staple.

Further aspects of the present invention will become apparent afterreview of the Detailed Description with reference to the followingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified perspective view of the human rotator cuff andassociated anatomical structure.

FIG. 2 is a schematic depiction of a full thickness tear in thesupraspinatus tendon of the rotator cuff of FIG. 1.

FIG. 3 is a stylized anterior view of a patient with a shoulder ofpatient being shown in cross-section for purposes of illustration.

FIG. 4 is a stylized anterior view of a shoulder including a humerus anda scapula. The head of the humerus is shown mating with the glenoidfossa of the scapula at a glenohumeral joint and a sheet-like materialis fixed to the tendon.

FIG. 5 is a stylized perspective view illustrating an exemplaryprocedure for treating a shoulder of a patient.

FIG. 6 is a stylized perspective view of a shoulder including asupraspinatus having a distal tendon with a sheet-like material fixedthereto. A proximal end of the supraspinatus is fixed to the scapula andthe distal tendon of the supraspinatus is fixed to the humerus.

FIG. 7A, FIG. 7B, and FIG. 7C are multiple plan views illustrating anexemplary staple in accordance with the present detailed description.

FIG. 8 is a perspective view further illustrating the staple shown inthe previous Figure.

FIG. 9 is a perspective view showing a staple push rod that may be usedin conjunction with the staple shown in the previous Figure.

FIG. 10A and FIG. 10B illustrate multiple plan views of an exemplaryfixation tool in accordance with the present detailed description.

FIG. 11A is a further enlarged partial cross-sectional view of a distalportion of the fixation tool shaft shown in the previous Figure.

FIG. 11B is an additional partial cross-sectional view showing a staplecarried by a staple push rod and a fixation tool shaft disposed aboutthe staple push rod.

FIG. 12A through FIG. 12C are a sequence of plan views illustrating anexemplary method and apparatus in accordance with the present detaileddescription.

FIG. 13A, FIG. 13B, FIG. 13C and FIG. 13D are multiview projectionsillustrating a fixation tool shaft shown in the previous Figures.

FIG. 14 is an enlarged axial view of the fixation tool shaft shown inthe previous Figure.

FIG. 15 is an additional enlarged axial view of the fixation tool shaftshown in the previous Figure.

FIG. 16 is an exploded isometric view of an exemplary fixation tool inaccordance with this detailed description.

DETAILED DESCRIPTION OF THE INVENTION

The following detailed description should be read with reference to thedrawings in which similar elements in different drawings are numberedthe same. The drawings, which are not necessarily to scale, depictillustrative embodiments and are not intended to limit the scope of theinvention.

As used herein, the term “tissue” refers to soft tissue, such as atendon, and/or bone tissue, depending on the context in which it isused.

FIG. 3 is a stylized anterior view of a patient 20. For purposes ofillustration, a shoulder 22 of patient 20 is shown in cross-section inFIG. 3. Shoulder 22 includes a humerus 14 and a scapula 12. In FIG. 3, ahead 24 of humerus 14 can be seen mating with a glenoid fossa of scapula12 at a glenohumeral joint. With reference to FIG. 3, it will beappreciated that the glenoid fossa comprises a shallow depression inscapula 12. The movement of humerus 14 relative to scapula 12 iscontrolled by a number of muscles including: the deltoid, thesupraspinatus, the infraspinatus, the subscapularis, and the teresminor. For purposes of illustration, only the supraspinatus 26 is shownin FIG. 3.

With reference to FIG. 3, it will be appreciated that a distal tendon 28of the supraspinatus 26 meets humerus 14 at an insertion point. Scapula12 of shoulder 22 includes an acromium 32. In FIG. 3, a subacromialbursa 34 is shown extending between acromium 32 of scapula 12 and head24 of humerus 14. In FIG. 3, subacromial bursa 34 is shown overlayingsupraspinatus 26. Subacromial bursa 34 is one of the hundreds of bursaefound the human body. Each bursa comprises a fluid filled sac. Thepresence of these bursae in the body reduces friction between bodilytissues. Injury and/or infection of the bursa can cause it to becomeinflamed. This condition is sometimes referred to as bursitis.

The exemplary methods and apparatus described herein may be used to fixtendon repair implants to various target tissues. For example, a tendonrepair implant may be fixed to one or more tendons associated with anarticulating joint, such as the glenohumeral joint. The tendons to betreated may be torn, partially torn, have internal micro-tears, beuntorn, and/or be thinned due to age, injury or overuse. Applicantsbelieve that the methods and apparatus of the present application andrelated devices may provide very beneficial therapeutic effect on apatient experiencing joint pain believed to be caused by partialthickness tears and/or internal microtears. By applying a tendon repairimplant early before a full tear or other injury develops, the implantmay cause the tendon to thicken and/or at least partially repair itself,thereby avoiding more extensive joint damage, pain, and the need formore extensive joint repair surgery.

FIG. 4 is a stylized anterior view of a shoulder 22 including a humerus14 and a scapula 12. In FIG. 4, a head 24 of humerus 14 is shown matingwith a glenoid fossa of scapula 12 at a glenohumeral joint. Asupraspinatus 26 is also shown in FIG. 4. This muscle (along withothers) control the movement of humerus 14 relative to scapula 12. Adistal tendon 28 of supraspinatus 26 meets humerus 14 at an insertionpoint 30.

In the embodiment of FIG. 4, distal tendon 28 includes a first damagedportion 36. A number of loose tendon fibers 40 in first damaged portion36 are visible in FIG. 4. First damaged portion 36 includes a first tear42 extending partially through distal tendon 28. First tear 42 maytherefore be referred to as a partial thickness tear. With reference toFIG. 4, it will be appreciated that first tear 42 begins on the side ofdistal tendon 28 facing the subacromial bursa (shown in the previousFigure) and ends midway through distal tendon 28. Accordingly, firsttear 42 may be referred to as a bursal side tear.

With reference to FIG. 4, it will be appreciated that distal tendon 28includes a second damaged portion 38 located near insertion point 30. Inthe embodiment of FIG. 4, second damaged portion 38 of distal tendon 28has become frayed and a number of loose tendon fibers 40 are visible inFIG. 4. Second damaged portion 38 of distal tendon 28 includes secondtear 44. With reference to FIG. 4, it will be appreciated that secondtear 44 begins on the side of distal tendon 28 facing the humerus 14.Accordingly, second damaged portion 38 may be referred to as anarticular side tear.

In the embodiment of FIG. 4, a sheet-like implant 50 has been placedover the bursal side of distal tendon 28. With reference to FIG. 4, itwill be appreciated that sheet-like implant 50 extends over insertionpoint 30, first tear 42 and second tear 44. Some useful methods inaccordance with this detailed description may include placing a tendonrepair implant on the bursal side of a tendon regardless of whether thetears being treated are on the bursal side, articular side or within thetendon. In some cases the exact location and nature of the tears beingtreated may be unknown. A tendon repair implant may be applied to thebursal side of a tendon to treat shoulder pain that is most likelycaused by one or more partial thickness tears in the tendon. In theembodiment of FIG. 4, sheet-like implant 50 is fixed to distal tendon 28and to humerus 14 by a plurality of staples 100 as described herein indetail.

FIG. 5 is a stylized perspective view illustrating an exemplaryprocedure for treating a shoulder 22 of a patient 20. The procedureillustrated in FIG. 5 may include, for example, fixing tendon repairimplants to one or more tendons of shoulder 22. The tendons treated maybe torn, partially torn, have internal micro-tears, be untorn, and/or bethinned due to age, injury or overuse.

Shoulder 22 of FIG. 5 has been inflated to create a cavity therein. Inthe exemplary embodiment of FIG. 5A, a fluid supply 52 is pumping acontinuous flow of saline into the cavity. This flow of saline exits thecavity via a fluid drain 54. A camera 56 provides images from inside thecavity. The images provided by camera 56 may be viewed on a display 58.

Camera 56 may be used to visually inspect the tendons of shoulder 22 fordamage. A tendon repair implant in accordance with this disclosure maybe fixed to a bursal surface of the tendon regardless of whether thereare visible signs of tendon damage. Applicants believe that the methodsand apparatus of the present application and related devices may providevery beneficial therapeutic effect on a patient experiencing joint painbelieved to be caused by internal microtears, but having no clear signsof tendon tears. By applying a tendon repair implant early before a fulltear or other injury develops, the implant may cause the tendon tothicken and/or at least partially repair itself, thereby avoiding moreextensive joint damage, pain, and the need for more extensive jointrepair surgery.

A delivery system 60 can be seen extending from shoulder 22 in FIG. 5.Delivery system 60 comprises a sheath that is fixed to a handle. Thesheath defines a lumen and a distal opening fluidly communicating thelumen. In the embodiment of FIG. 5, the distal opening of the sheath hasbeen placed in fluid communication with the cavity created in shoulder22.

A tendon repair implant is at least partially disposed in the lumendefined by the sheath of delivery system 60. Delivery system 60 can beused to place the tendon repair implant inside shoulder 22. Deliverysystem 60 can also be used to hold the tendon repair implant against thetendon. In some embodiments, the tendon repair implant is folded into acompact configuration when inside the lumen of the sheath. When this isthe case, delivery system 60 may be used to unfold the tendon repairimplant into an expanded shape.

The tendon repair implant may be fixed to the tendon while it is heldagainst the tendon by delivery system 60. Various attachment elementsmay be used to fix the tendon repair implant to the tendon. Examples ofattachment elements that may be suitable in some applications includesutures, tissue anchors, bone anchors, and staples. In the exemplaryembodiment of FIG. 5, the shaft of a fixation tool 70 is shown extendinginto shoulder 22. In one exemplary embodiment, fixation tool 70 iscapable of fixing the tendon repair implant to the tendon with one ormore staples while the tendon repair implant is held against the tendonby delivery system 60.

FIG. 6 is a stylized perspective view of a shoulder 22 including asupraspinatus 26 having a distal tendon 28. With reference to FIG. 6, itwill be appreciated that a tendon repair implant 50 has been fixed to asurface of distal tendon 28. Tendon repair implant 50 may comprise, forexample, various sheet-like structures without deviating from the spiritand scope of the present detailed description. In some usefulembodiments, the sheet-like structure may comprise a plurality offibers. The fibers may be interlinked with one another. When this is thecase, the sheet-like structure may comprise a plurality of aperturescomprising the interstitial spaces between fibers. Various processes maybe used to interlink the fibers with one another. Examples of processesthat may be suitable in some applications including weaving, knitting,and braiding. In some embodiment, the sheet-like structure may comprisea laminate including multiple layers of film with each layer of filmdefining a plurality of micro-machined or formed holes. The sheet-likestructure of the tendon repair implant may also comprise a plurality ofelectro-spun nanofiber filaments forming a composite sheet.Additionally, the sheet-like structure may comprise a synthetic spongematerial that defines a plurality of pores. The sheet-like structure mayalso comprise a reticulated foam material. Reticulated foam materialsthat may be suitable in some applications are available from BiomerixCorporation of Freemont, Calif. which identifies these materials usingthe trademark BIOMATERIAL™.

Various attachment elements may be used to fix tendon repair implant 50to distal tendon 28 without deviating from the spirit and scope of thisdetailed description. Examples of attachment elements that may besuitable in some applications include sutures, tissue anchors, boneanchors, and staples. In the exemplary embodiment of FIG. 6, a pluralityof staples 100 are fixing tendon repair implant 50 to distal tendon 28.In some exemplary methods, a plurality of staples 100 may be appliedusing a fixation tool. The fixation tool may then be withdrawn from thebody of the patient. Distal tendon 28 meets humerus 14 at an insertionpoint 30. With reference to FIG. 6, it will be appreciated thatsheet-like implant 50 extends over insertion point 30. Tendon repairimplant may be applied to distal tendon 28, for example, using theprocedure illustrated in the previous Figure.

FIG. 7A, FIG. 7B, and FIG. 7C are multiple plan views illustrating anexemplary staple 100 in accordance with the present detaileddescription. FIG. 7A, FIG. 7B, and FIG. 7C may be collectively referredto as FIG. 7. A proximal direction is illustrated with an arrow P inFIG. 7. A distal direction is illustrated with a second arrow D in FIG.7.

Staple 100 comprises a first arm 102A, a second arm 102B, and a bridge104 extending from the proximal end of first arm 102A to the proximalend of second arm 102B. The distal end of first arm 102A abuts theproximal end of a first fluke 106A. Similarly, the distal end of secondarm 102B abuts the proximal end of a second fluke 106B. In FIG. 7, firstfluke 106A and second fluke 106B are shown extending distally from firstarm 102A and second arm 102B, respectively. With reference to FIG. 7, itwill be appreciated that first fluke 106A has a lateral extent that islarger than a lateral extent of first arm 102A. First fluke 106A ismounted eccentrically to first arm 102A in the embodiment of FIG. 7.Second fluke 106B is mounted eccentrically to second arm 102B and secondfluke 106B has a lateral extent that is larger than a lateral extent ofsecond arm 102B. First fluke 106A includes a first proximal surface 108Aprojecting at an outward angle in a proximal direction away from thedistal end of first arm 102A. Second fluke 106B includes a secondproximal surface 108B projecting at an outward angle in a proximaldirection away from the distal end of second arm 102B.

With reference to FIG. 7A, it will be appreciated that first fluke 106Aincludes a first point 120A and a first barb 122A. Second fluke 106Bincludes a second point 120B and a second barb 122B. In FIG. 7, firstpoint 120A and second point 120B are shown generally pointing in thedistal direction indicated by arrow D. Also in FIG. 7, first barb 122Aand second barb 122B are shown generally pointing in the proximaldirection indicated by arrow P.

With reference to FIG. 7A it will be appreciated that first fluke 106Adefines a first passageway 124A and second fluke 106B defines a secondpassageway 124B. In the exemplary embodiment of FIG. 7, first passageway124A extends through first fluke 106A and second passageway 124B extendsthrough second fluke 106B. It will be appreciated, however, that firstpassageway 124A may extend through other portions of staple 100 in someembodiments. Similarly, second passageway 124B may extend through otherportions of staple 100 in some embodiments. With reference to FIG. 7B itwill be appreciated that, first passageway 124A and second passageway124B each have a generally square cross-sectional shape. It will beappreciated, however, that first passageway 124A and second passageway124B may have various cross-sectional shapes without deviating from thespirit and scope of the present detailed description. Further, eachpassageway can extend partially through the length of each fluke ratherthan all the way through to provide a cavity rather than a passageway.

With reference to FIG. 7C, it will be appreciated that first barb 122Aof first fluke 106A defines a first notch 126A. In the exemplaryembodiment of FIG. 7, first notch 126A divides first barb 122A into afirst sub-barb and a second sub-barb. Second barb 122B of second fluke106B defines a second notch 126B. In the exemplary embodiment of FIG. 7,second notch 126B divides second barb 122B into a first sub-barb and asecond sub-barb.

FIG. 8 is a perspective view showing staple 100 shown in the previousFigure. Staple 100 comprises a first arm 102A, a second arm 102B, and abridge 104 extending from the proximal end of first arm 102A to theproximal end of second arm 102B. The distal end of first arm 102A abutsthe proximal end of a first fluke 106A. With reference to FIG. 8 it willbe appreciated that first fluke 106A defines a first passageway 124A. Inthe exemplary embodiment of FIG. 8, first passageway 124A has agenerally square cross-sectional shape. It will be appreciated, however,that first passageway 124A may have various cross-sectional shapeswithout deviating from the spirit and scope of the present detaileddescription.

A second fluke 106B extends distally from second arm 102B with theproximal end of second fluke 106B abutting the distal end of second arm102B. With reference to FIG. 8, it will be appreciated that second fluke106B has a lateral extent that is larger than a lateral extent of secondarm 102B. Second fluke 106B is mounted eccentrically to second arm 102Bin the embodiment of FIG. 8. Similarly, first fluke 106A is mountedeccentrically to first arm 102A and first fluke 106A has a lateralextent that is larger than a lateral extent of first arm 102A.

A proximal direction is illustrated with an arrow P in FIG. 8. A distaldirection is illustrated with a second arrow D in FIG. 8. With referenceto FIG. 8A, it will be appreciated that first fluke 106A of first arm102A includes a first point 120A and a first barb 122A. Second fluke106B includes a second point 120B and a second barb 122B. In FIG. 8,first point 120A and second point 120B are shown generally pointing inthe distal direction indicated by arrow D. Also in FIG. 8, first barb122A and second barb 122B are shown generally pointing in the proximaldirection indicated by arrow P. With reference to FIG. 8, it will beappreciated that first fluke 106A includes a first proximal surface 108Aprojecting at an outward angle in a proximal direction away from thedistal end of first arm 102A. Second fluke 106B includes a secondproximal surface 108B projecting at an outward angle in a proximaldirection away from the distal end of second arm 102B.

FIG. 9 is a perspective view showing a staple push rod 130 that may beused in conjunction with staple 100 shown in the previous Figure. Staplepush rod 130 includes a shaft 132 and a pair of stakes 134 extendingdistally beyond a distal end of shaft 132. The distal direction isindicated with an arrow D in FIG. 9. Stakes 134 include a first stake134A and a second stake 134B. First stake 134A and second stake 134Bform a fork 136.

In the embodiment of FIG. 9, each stake 134 has a distal portion 138 anda proximal portion 140. In some useful embodiments, each distal portion138 is dimensioned to extend into a passage defined by a staple. In theembodiment of FIG. 9, each proximal portion 140 has a width larger thana width of each distal portion 138 so that a shoulder of each proximalportion 140 contacts a proximal surface of the staple to apply pushingforces thereto. First stake 134A comprises a first shoulder 142A andsecond stake 134B comprises a second shoulder 142B. Although depicted asa shoulder to provide pushing force to the staple, other designs can beutilized. For example, any larger cross section proximal portion canprovide a pushing force, such as a conical increase in profile. In theembodiment of FIG. 9, proximal portion 140 of first stake 134A and theproximal portion 140 of second stake 134B diverge from one another asthey extend in distal direction D away from shaft 132. In someapplications, this arrangement may cause pushing forces applied to twoflukes of a staple to have a laterally outward component.

In FIG. 9, first stake 134A and second stake 134B are shown assuming asubstantially unstressed state. It will be appreciated that first stake134A and second stake 134B can be resiliently urged to assume shapesother than the shape shown in FIG. 9. For example, first stake 134A andsecond stake 134B may be urged together so that fork 136 can be insertedinto a lumen having a diameter smaller than the distance between thedistal points of first stake 134A and second stake 134B shown in FIG. 9.

FIG. 10A and FIG. 10B illustrate multiple plan views of an exemplaryfixation tool 144 in accordance with the present detailed description.Fixation tool 144 incorporates staple push rod 130 and is useful indelivering staple 100. FIG. 10A and FIG. 10B may be referred tocollectively as FIG. 10. It is customary to refer to multi-viewprojections using terms such as front view, top view, and side view. Inaccordance with this convention, FIG. 10A may be referred to as a topview of fixation tool 144 and FIG. 10B may be referred to as a side viewof fixation tool 144. The terms top view and side view are used hereinas a convenient method for differentiating between the views shown inFIG. 10. It will be appreciated that the elements shown in FIG. 10 mayassume various orientations without deviating from the spirit and scopeof this detailed description. Accordingly, the terms top view and sideview should not be interpreted to limit the scope of the inventionrecited in the attached claims.

In the embodiment of FIG. 10, fixation tool 144 comprises a pilot memberor fixation tool shaft 146 that is attached to a handle 148. Fixationtool shaft 146 comprises a wall 150 defining a lumen 152. With referenceto FIG. 10, it will be appreciated that fixation tool shaft 146 includesa first prong 154A and a second prong 156B that extend distally beyond adistal end 158 of lumen 152.

In FIG. 10, a staple 100 can be seen residing in lumen 152 of fixationtool shaft 146. For purposes of illustration, a distal portion offixation tool shaft 146 is enlarged in FIG. 10 to better show staple100. Staple 100 comprises a first aim 102A, a second arm 102B, and abridge 104 extending from the proximal end of first arm 102A to theproximal end of second arm 102B. The distal end of first arm 102A abutsthe proximal end of a first fluke 106A. Similarly, the distal end ofsecond arm 102B abuts the proximal end of a second fluke 106B. In FIG.10, first fluke 106A and second fluke 106B are shown extending distallyfrom first arm 102A and second arm 102B, respectively.

Staple push rod 130 includes a shaft 132 and a pair of stakes 134extending distally beyond a distal end of shaft 132. The distaldirection is indicated with an arrow D in FIG. 10. Stakes 134 include afirst stake 134A and a second stake 134B. In FIG. 10, a distal portionof each stake 134 can be seen extending through a passageway defined bystaple 100. In the embodiment of FIG. 10, a trigger 160 is pivotablycoupled to handle 148 of fixation tool 144. Trigger 160 is operativelycoupled to staple push rod 130. In operation, staple push rod 130 willbe advanced and/or retracted in an axial direction when trigger 160 ispivoted relative to handle 148.

FIG. 11A is a further enlarged top view of a distal portion of fixationtool shaft 146 shown in the previous Figure. For purposes ofillustration, fixation tool shaft 146 is shown in partial cross-sectionin FIG. 11A so that staple 100 is visible residing in lumen 152. Withreference to FIG. 11A, it will be appreciated that staple 100 isdisposed on a distal portion of staple push rod 130. Staple 100comprises a first arm 102A, a second arm 102B, and a bridge 104extending from the proximal end of first arm 102A to the proximal end ofsecond arm 102B. The distal end of first arm 102A abuts the proximal endof a first fluke 106A. Similarly, the distal end of second arm 102Babuts the proximal end of a second fluke 106B. In FIG. 11, first fluke106A and second fluke 106B are shown extending distally from first arm102A and second aim 102B, respectively.

First fluke 106A of staple 100 defines a first passageway 124A. In FIG.11A, a distal portion 138 of first stake 134A of staple push rod 130 canbe seen extending through first passageway 124A defined by first fluke106A. A distal portion 138 of second stake 134B of staple push rod 130can be seen extending through a second passageway 124B defined by secondfluke 106B of staple 100.

In FIG. 11A, a first shoulder 142A of first stake 134A is showncontacting proximal surface 108 of first fluke. Distal portion 138 offirst stake 134A extends distally of first shoulder 142A and proximalportion 140 of first stake 134A extends proximally of first shoulder142A. In some useful embodiments, the proximal portion of first stake134A has a first thickness and the distal portion of first stake 134Ahas a second thickness different from the first thickness. In someparticularly useful embodiments, the second thickness is less than thefirst thickness. In some applications, this may increase the flexibilityof the distal portion of first stake 134A so that it bends more easily,and so that it withdraws from the staple with minimal force.

A second shoulder 142B of second stake 134B is shown contacting proximalsurface 108 of second fluke 106 in FIG. 11A. A distal portion 138 ofsecond stake 134B extends distally of second shoulder 142B and aproximal portion 140 of second stake 134B extends proximally of secondshoulder 142B. In some useful embodiments, the proximal portion ofsecond stake 134B has a first thickness and the distal portion of secondstake 134B has a second thickness different from the first thickness. Insome particularly useful embodiments, the second thickness is less thanthe first thickness. In some applications, this may increase theflexibility of the distal portion of first stake 134A so that it bendsmore easily, and so that it withdraws from the staple with minimalforce.

With reference to FIG. 11A, it will be appreciated that there is a gap Gbetween staple push rod 130 and bridge 104 of staple 100. In someapplications, gap G allows staple 100 to be placed in tension withoutbridge 104 contacting staple push rod 130. Staple 100 may be placed intension, for example, as staple 100 is advanced into a target tissue.

FIG. 11B is an additional top view showing a distal portion of fixationtool shaft 146, staple push rod 130, and staple 100. By comparing FIG.11A and FIG. 11B, it will be appreciated that staple push rod 130 andstaple 100 have been advanced in a distal direction D relative tofixation tool shaft 146. In FIG. 11B, staple 100 is shown extending outof lumen 152 defined by fixation tool shaft 146.

In FIG. 11B, a distal portion 138 of first stake 134A of staple push rod130 can be seen extending through a first passageway 124A defined byfirst fluke 106A of staple 100. In FIG. 11B, a first shoulder 142A offirst stake 134A is shown contacting proximal surface 108 of first fluke106A. Distal portion 138 of first stake 134A extends distally of firstshoulder 142A and proximal portion 140 of first stake 134A extendsproximally of first shoulder 142A. In some useful embodiments, theproximal portion of first stake 134A has a first width and the distalportion of first stake 134A has a second width different from the firstwidth. In some particularly useful embodiments, the first width isgreater than the first width. The arrangement allows the proximalportion of stake to engage a proximal surface of the staple to applypushing forces to the staple.

In FIG. 11B, a distal portion 138 of second stake 134B of staple pushrod 130 can be seen extending through a second passageway 124B definedby second fluke 106B of staple 100. In FIG. 11B, a second shoulder 142Bof second stake 134B is shown contacting proximal surface 108 of secondfluke 106B. In the embodiment of FIG. 11B, proximal portion 140 ofsecond stake 134B may apply pushing force to proximal surface 108 ofsecond stake 134B. Proximal portion 140 of second stake 134B extendsproximally of second shoulder 142B and distal portion 138 of secondstake 134B extends distally of second shoulder 142B. In the embodimentof FIG. 11B, proximal portion 140 of second stake 134B has a widthlarger than the width of distal portion 138 of second stake 134B so thatthe shoulder 142 of second stake 134B contacts proximal surface 108 ofsecond fluke 106B to apply pushing forces thereto.

In the embodiment of FIG. 11B, first stake 134A and second stake 134Bare in a substantially unstressed state. It will be appreciated thatfirst stake 134A and second stake 134B can be resiliently urged toassume shapes other than the shape shown in FIG. 11. For example, firststake 134A and second stake 134B may be urged together so that fork 136of staple push rod 130 and staple 100 can be inserted into lumen 152defined by fixation tool shaft 146.

With reference to FIG. 11B, it will be appreciated that there is a gap Gbetween staple push rod 130 and bridge 104 of staple 100. In someapplications, gap G allows staple 100 to be placed in tension withoutbridge 104 contacting staple push rod 130. In some applications, placingstaple 100 under tension may urge first fluke 106 and second fluke 106into orientations which lock staple 100 into a target tissue. Forexample, first fluke 106A and second fluke 106B may be rotated so that abarb of each fluke engages the target tissue. When this is the case, thetension on the staple may keep first fluke 106A and second fluke 106B inthe rotated position. Also when this is the case, the barbs of therotated flukes may inhibit staple pullout.

FIG. 12A through FIG. 12C are a sequence of plan views illustrating anexemplary method in accordance with the present detailed description.FIG. 12A, FIG. 12B, and FIG. 12C may be collectively referred to as FIG.12. The exemplary method illustrated in FIG. 12 may be used, forexample, to fix a tendon repair implant 50 to a target tissue T using astaple 100.

At FIG. 12A, a fixation tool 144 has been used to form a first pilothole 162A and a second pilot hole 162B in target tissue T. In theembodiment of FIG. 12, fixation tool 144 includes a fixation tool shaft146 comprising a wall 150 defining a lumen 152. With reference to FIG.12, it will be appreciated that fixation tool shaft 146 includes a firstprong 154A and a second prong 156B that extend distally beyond a distalend 158 of lumen 152. In the embodiment of FIG. 12A, first prong 154Aand second prong 156B have been urged into tissue T to form first pilothole 162A and second pilot hole 162B. In FIG. 12A a distally directedforce F applied to fixation tool shaft 146 is illustrated using anarrow. Force F may be produced, for example, by pushing on a handle thatis fixed to a proximal portion of fixation tool shaft 146. It will beappreciated that in some embodiments, such as the embodiment depicted inFIG. 6, one of the first and second pilot holes may be formed throughthe sheet-like implant and the target tissue, and the other pilot holemay be formed directly in the target tissue without passing through thesheet-like implant. In other words, in various embodiments staples maystraddle the perimeter edge of the sheet-like implant (as shown in FIG.6), may be applied adjacent to the perimeter, and/or be applied to acentral region of the implant. In some embodiments, the staples may beused to attach the implant to soft tissue and/or to bone. In FIG. 12A, astaple 100 can be seen residing in lumen 152 of fixation tool shaft 146.For purposes of illustration, fixation tool shaft 146 is shown inpartial cross-section in FIG. 12A so that staple 100 is visible residingin lumen 152. With reference to FIG. 12, it will be appreciated thatstaple 100 is carried by a fork 136 comprising a first stake 134A and asecond stake 134B. In FIG. 12A, a distal portion of first stake 134A ofstaple push rod 130 can be seen extending through a first passagewaydefined by first fluke 106A. A distal portion of second stake 134B ofstaple push rod 130 can be seen extending through a second passagewaydefined by second fluke 106B of staple 100.

In some useful embodiments, each stake is positioned relative to a prongalong an inner surface of fixation tool shaft 146 so that the stakesadvance into the pilot holes when the stakes are moved in a distaldirection. Staple push rod 130 is slidably disposed within lumen 152defined by along fixation tool shaft 146. Fixation tool 144 includes amechanism that is capable of creating relative axial motion betweenstaple push rod 130 and fixation tool shaft 146 so that staple push rod130 slides along fixation tool shaft 146.

At FIG. 12B, relative motion has been created between staple push rod130 and fixation tool shaft 146 while distally directed force F has beencontinuously applied to fixation tool shaft 146. By comparing FIG. 12Band FIG. 12A, it will be appreciated that first stake 134A and secondstake 134B have been advanced in a distal direction D. With reference toFIG. 12, it will also be appreciated that first stake 134A and secondstake 134B have advanced into first pilot hole 162A and second pilothole 162B, respectively. In FIG. 12B, first fluke 106A is shown residingin first pilot hole 162. Second fluke 106B is residing in second pilothole 162 in the embodiment of FIG. 12B.

At FIG. 12C, additional relative motion has been created between staplepush rod 130 and fixation tool shaft 146 while distally directed force Fhas been continuously applied to fixation tool shaft 146. By comparingFIG. 12C and FIG. 12B, it will be appreciated that the relative motionbetween staple push rod 130 and fixation tool shaft 146 has movedfixation tool shaft 146 in a proximal direction P.

By comparing FIG. 12C and FIG. 12B, it will also be appreciated thatfirst arm 102A of staple 100 has been bent and first fluke 106A has beenrotated to a toggled position. In the exemplary embodiment of FIG. 12C,force applied to first fluke 106A by first shoulder 142A has causedfirst fluke 106A to rotate. Also in the embodiment of FIG. 12C, therotation of first fluke 106A has caused some bending in the distalportion 138 of first stake 134A. With continuing reference to FIG. 12Cand FIG. 12B, it will be appreciated that second arm 102B of staple 100has been bent and second fluke 106A has been rotated to a toggledposition. In the exemplary embodiment of FIG. 12C, force applied tosecond fluke 106 b by second shoulder 142B has caused second fluke 106Bto rotate. Also in the embodiment of FIG. 12C, the rotation of secondfluke 106B has caused some bending in the distal portion 138 of secondstake 134B.

With reference to FIG. 12C, it will be appreciated that a first throughhole 164A and a second through hole 164B have been formed in tendonrepair implant 50. In the embodiment of FIG. 12, first through hole 164Aand a second through hole 164B were created by urging first prong 154Aand second prong 156B of fixation tool shaft 146 through tendon repairimplant 50.

FIG. 13A, FIG. 13B, and FIG. 13C are multiview projections illustratinga fixation tool shaft 146 shown in the previous Figures. FIG. 13D is across-sectional view of fixation tool shaft 146 sectioned along cuttingplane D-D illustrated in FIG. 13C. These Figures may be collectivelyreferred to as FIG. 13. Fixation tool shaft 146 of FIG. 13 comprises awall 150 defining a lumen 152. A first prong 154A and a second prong156B of fixation tool shaft 146 extend distally beyond a distal end 158of lumen 152.

With reference to FIG. 13, it will be appreciated that fixation toolshaft 146 comprises a proximal portion 170, a distal portion 168 and anintermediate portion 166 disposed between proximal portion 170 anddistal portion 168. In the embodiment of FIG. 13, distal portion 168 hasan axial extent DA, a major lateral extent LA and a minor lateral extentLB. With reference to FIG. 13, it will be appreciated that axial extentDA is greater than both minor lateral extent LB and major lateral extentLA.

FIG. 14 is an enlarged axial view of fixation tool shaft 146 shown inthe previous Figure. With reference to FIG. 14, it will be appreciatedthat proximal portion 170 of fixation tool shaft 146 comprises a wall150 having an outer surface 172. In FIG. 14, outer surface 172 isillustrated using a circle. Thus, it will be appreciated that proximalportion 170 of fixation tool shaft 146 has a generally cylindrical outershape in the exemplary embodiment of FIG. 14. In the exemplaryembodiment of FIG. 14, fixation tool shaft 146 has a generally uniformwall thickness. Accordingly, the shape of proximal portion 170 may begenerally described as a cylindrical tube. The shape of distal portion168 may be described as a cylindrical-tube that has been partiallyflattened. In the exemplary embodiment of FIG. 14, distal portion 168 offixation tool shaft 146 has a major lateral extent LA and a minorlateral extent LB. With reference to FIG. 14, it will be appreciatedthat major lateral extent LA is greater than minor lateral extent LB.

FIG. 15 is an additional enlarged axial view of fixation tool shaft 146.With reference to FIG. 15, it will be appreciated that distal portion168 of fixation tool shaft 146 comprises a first major side SA, a secondmajor side SB, a first minor side SC, and a second minor side SD. In theexemplary embodiment of FIG. 15, each minor side has a first centralradius RA and each major side has a second central radius RB. Withreference to FIG. 15, it will be appreciated that second central radiusRB is greater than first central radius RA. In the exemplary embodimentof FIG. 15, first major side SA, second major side SB, first minor sideSC, and second minor side SD each have a generally convex shape. In theexemplary embodiment of FIG. 15, each minor side is generally moreconvex than each major side.

FIG. 16 is an exploded isometric view of an exemplary fixation tool 144in accordance with this detailed description. In the embodiment of FIG.16, fixation tool 144 comprises a fixation tool shaft 146 and a handle148. In FIG. 16, handle 148 is exploded into two pieces. A proximalportion of fixation tool shaft 146 is fixed to handle 148 when fixationtool 144 is in an assembled state. Fixation tool shaft 146 comprises awall 150 defining a lumen 152. With reference to FIG. 16, it will beappreciated that fixation tool shaft 146 includes a first prong 154A anda second prong 156B that extend distally beyond a distal end 158 oflumen 152.

When fixation tool 144 is in an assembled state a staple push rod 130extends into lumen 152 of fixation tool shaft 146. Staple push rod 130comprises a fork 136 and a shaft 132. Fork 136 comprises a first stake134A and a second stake 134B. Shaft 132 is coupled between fork 136 anda lever 174. Lever 174 is coupled to a trigger 160. Trigger 160 ispivotably coupled to handle 148 of fixation tool 144 when fixation tool144 is in an assembled state. In operation, staple push rod 130 will beadvanced and/or retracted in an axial direction when trigger 160 ispivoted relative to handle 148.

While exemplary embodiments of the present invention have been shown anddescribed, modifications may be made, and it is therefore intended inthe appended claims and subsequently filed claims to cover all suchchanges and modifications which fall within the true spirit and scope ofthe invention.

What is claimed is:
 1. A method for attaching a sheet-like implant to atarget tissue, comprising the steps of: providing a device including apilot member having a distal end and at least a pair of prongs extendingfrom the distal end of the pilot member; the device further including astaple push rod carrying a staple, the staple having a first arm havinga proximal end and a distal end, and a second arm having a proximal endand a distal end with a bridge extending from the proximal end of thefirst arm to the proximal end of the second arm and staple retentionmeans proximate the distal end of each arm wherein the staple push rodlongitudinally engages the staple; piercing the target tissue with thefirst prong to create a first pilot hole and piercing the target tissuewith the second prong to create a second pilot hole; positioning thedistal end of the first arm near the first pilot hole and positioningthe distal end of the second arm near the second pilot hole; advancingthe staple push rod in a distal direction so that the push rod appliespushing forces to the staple to advance at least a portion of the firstleg and the second leg into the pilot holes with the staple retentionmeans engaging the tissue walls of the pilot holes for retention.
 2. Themethod of claim 1, wherein the pushing force is applied to a surface oneach leg of the staple proximate its distal end.
 3. The method of claim2, wherein the pushing force has a direction that is generally parallelto a central axis of the first and second pilot holes.
 4. The method ofclaim 3, wherein the legs are advanced into the pilot holes while theprongs are disposed in the pilot holes.
 5. The method of claim 4,further comprising the step of moving the pilot member in a proximaldirection relative to the target tissue until a distal end of the firstprong is located proximal of the first leg and a distal end of thesecond prong is located proximal of the second leg.
 6. The method ofclaim 5, wherein the step of advancing the staple push rod in a distaldirection comprises actuating a mechanism that produces relative motionbetween the staple push rod and the pilot member while applying adistally directed force to the pilot member.
 7. The method of claim 5,wherein moving the pilot member in a proximal direction relative to thetarget tissue comprises producing relative motion between the staplepush rod and the pilot member while applying a distally directed forceto the pilot member.
 8. A method for attaching a sheet-like implant to atarget tissue, comprising the steps of: providing an device including apilot member having a distal end and at least a pair of prongs extendingfrom the distal end of the pilot member; the device further including astaple push rod carrying a staple, the staple comprising a first armhaving a proximal end and a distal end, and a second arm having aproximal end and a distal end with a bridge extending from the proximalend of the first arm to the proximal end of the second arm, a firstfluke of the staple having a proximal end abutting the distal end of thefirst arm, and a second fluke of the staple having a proximal endabutting the distal end of the second arm; the staple push rod of thedevice including a pair of stakes, each stake having a distal portionand a proximal portion, each distal portion extending into a passagedefined by a fluke, each proximal portion having a width larger than awidth of each distal portion so that a shoulder of each proximal portioncontacts a distal surface of a fluke; piercing the target tissue withthe first prong to create a first pilot hole and piercing the targettissue with the second prong to create a second pilot hole; positioningthe first fluke near the first pilot hole and positioning the secondfluke near the second pilot hole; advancing the staple push rod in adistal direction so that the stakes apply pushing forces to the flukescausing the flukes to advance into the pilot holes and causing the firstarm, the second arm, and the bridge to be placed in tension; the firstarm providing a first reaction force when placed in tension and thesecond arm providing a second reaction force when placed in tension; thepushing forces and reaction forces cooperating to produce a momentapplied to each fluke, the moment applied to each fluke causing eachfluke to rotate so that each fluke assumes a locked position in whichthe longitudinal axis of each fluke is skewed relative to a longitudinalaxis of the pilot member.
 9. The method of claim 8, wherein: a firstmoment having a first direction is applied to the first fluke; a secondmoment having a second direction is applied to the second fluke; thefirst direction is different from the second direction.
 10. The methodof claim 9, wherein the first direction is generally opposite the seconddirection.
 11. The method of claim 9, wherein the first direction is aclockwise direction and the second direction is a counter-clockwisedirection.
 12. The method of claim 8, wherein a first pushing force isapplied to the proximal surface of the first fluke at a location that isoffset from the first arm.
 13. The method of claim 12, wherein the firstpushing force has a direction that is generally parallel to a centralaxis of the first pilot hole.
 14. The method of claim 8, wherein theflukes are advanced into the pilot holes while the prongs are disposedin the pilot holes.
 15. The method of claim 8, further comprising thestep of moving the pilot member in a proximal direction relative to thetarget tissue until a distal end of the first prong is located proximalof the first fluke and a distal end of the second prong is locatedproximally of the second fluke.
 16. The method of claim 15, wherein thestep of advancing the staple push rod in a staple push rod and the pilotmember while applying a distally directed force to the pilot member. 17.The method of claim 15, wherein moving the pilot member in a proximaldirection relative to the target tissue comprises producing relativemotion between the staple push rod and the pilot member while applying adistally directed force to the pilot member.
 18. The method of claim 15,wherein the first fluke assumes a first locking position and the secondfluke assumes a second locking position while a distal end of the firstprong is located proximal of the first fluke and a distal end of thesecond prong is located proximally of the second fluke.